West Townshend Stone Arch Bridge: Week 5

West Townshend Stone Arch Bridge: Week 5

With most of the large-scale "rough" demolition occurring in Week 4, with the removal of the concrete parapets and infill area, Week 5 began with the more fine tuned excavation that was required to expose the base of the arch span.

As with all aspects of removing the old material from near the arch itself, it is very time consuming and labor intensive, but the team did a wonderful job of clearing all of the dirt away from the span and off of the ledge that is the original base that the bridge was built on.

Great care was taken to clean the arch down to bare stone and mortar so that a full assessment of the condition of those elements could be performed. Ascertaining whether those key elements are structurally sound will help decide the course of the project moving forward.

Check out the Week 5 Recap and Time-Lapse YouTube videos below to see the work in progress!

All of the excess material needed to be removed from around the arch span and the ledge base to ensure that the support elements of the bridge are capable of being stabilized as construction begins.

In the photographs to the left and below, you can see an operators view of how precariously close to the arch span an excavator weighing over 30,000 pounds has to get to reach the river bed (left) and to be able to clean up to the arch (below)...this requires a well trained operator and a great deal of careful operation.

Once all of the excess bulk material (the original backfill) has been removed, in some areas to a depth of twenty feet below the previously finished road grade, the final cleaning and preparation work can begin in earnest.

The final phase of this fifth week of the renovation process ended with the team meticulously cleaning the voussoirs (the large stones in the arch ring) and chipping away any cracked or damaged mortar. You will notice in the photographs above and below how freshened the stones look once they are prepared for the next steps, especially keeping in mind...they have been covered by fill in the place they stand for well over 100 years.

As a point of interest, the general practice at the time the bridge was originally erected was to build it completely dry stacked (without mortar), so it makes this process all the more intriguing that the team will have to repoint all the mortar joints on both the top and bottom of the arch span. Repointing is essentially the process of repairing all of the mortar joints to help strengthen them. That will be part of the Week 6 Adventure...Stay Tuned!

The granite blocks laid out in the photograph below are the stones that have been removed from the spandrel walls and they will be reused in the reformation of those same walls during the restoration process.

More Photos of the Work In Progress!